1. Field of the Invention
The present invention relates, in general, to a method for preparing antibacterial and deodorant polyester useful for fiber and, more particularly, to an improvement in melt viscosity, along with the method.
2. Description of the Prior Art
Various microorganisms, such as bacteria and fungi, exist in all of the human living environments. Human skin is very susceptible to the microorganisms due to sweat, a good proliferative medium. Clothes are also a good target for the microorganisms whether they absorb sweat or not. For example, the clothes which absorb sweat well provide the microorganisms with good habitants, leading the fibril of the clothes to brittleness and stinking. Clothes serve to carry the microorganisms to human skin even though they are little absorbent of sweat. The microorganisms easily adhere to clothes or skin through vehicles and proliferate, causing diseases including skin troubles.
Accordingly, much research and study has been directed to the development of polymers for fiber which are neater, more pleasant and more sanitary. As a result, many functional fibers have been developed. Among them are deodorant fibers with antibacterial activity. These fibers are useful for a plurality of purposes ranging from bedclothes, such as quilt, matrix and cushion, clothes, such as underwear, hosiery and sport wears, interior cloths, such as wallpaper, carpets and curtains, household appliances, such as towels and dish cloths, to industrial materials, such as filters.
It is well known that antibacterial agents are added upon synthesis or compounding, to give antibacterial and deodorant polymers for fiber which overcome the problems attributable to the microorganisms such as bacteria and fungi, to an extent. For example, Japanese Pat. Laid-Open Publication No. Heisei 1-42288 introduces the addition of a slurry of antibacterial and deodorizing agent in reaction monomer at polymerizing process. This is problematic in many respects. First, the agent aggregates or reacts with catalyst upon polymerizing reaction, lowering fiber-making property. In addition, while making fibers, there occurs a lot of cut yarn in the presence of the agent. Further, most of the agent is distributed at the center of the cross section of the fiber, so that it does not make a great contribution to antibacterial activity.
The antibacterial activity of fiber can be achieved by making ion-exchangeable polyester fibers and treating them with copper salt and silver salt in water, as disclosed in Japanese Pat. Laid-Open Publication No. Sho. 54-38951. While such fibers undergo after-process such as dyeing, the antibacterial activity is however reduced and the resulting articles feel rough.
When being measured under the condition of 100 Rad/Sec at 285.degree. C., ordinary polyester chips show a melt viscosity ranging from about 2,800 to 3,000 poise. In contrast, the polyester chip comprising 3% by weight or more of antibacterial inorganic particles has a significant reduced melt viscosity, for example, 1,000 poise or less. Thus, such antibacterial polyester chips are of lower hardness than ordinary polyester chips and when they are fed into extruder processing part, the pressure of the pack is remarkably lowered to the extent that the fiber-making property is degraded. In addition, it is difficult to obtain fibers of uniform fitness by spinning such chips. In an extreme case, the chips comprising antibacterial agent lead to the generation of broken short fiber, leading pressure hunting, dropping and cut yarn, significantly decreasing work efficiency.